Thermionic tube and plate assembly for such tubes



Aug. 11, 1953 w. WlHTOL v 2,643,793

THERMIONIC TUBE AND PLATE ASSEMBLY FOR SUCH TUBES Filed May 6, 1950INVENTOR. 14/51. 278 W/HTOL I HIS .A TT'ORNE vs Patented Aug. 11, 1953THERMIONIO TUBE AND PLATE ASSEMBLY FOR- SUCH TUBES Weltis Wihtol,Redwood City, Calif., assignor to The Robert Dollar Company, RedwoodCity,

Calif., a corporation Application May 6, 1950, Serial No. 160,461

8 Claims.

This invention relates to thermionic tubes or like devices and toimproved plate assemblies for such tubes.

The principal object of the invention is'to provide an improvedthermionic tube and plate assembly therefore permitting a vastly greaterrate of heat dissipation than that found in any comparable prior artplate assembly.

A further object of the invention is to provide a thermionic tube inwhich the improved plate assembly and the glass envelope are so relatedthat they cooperate to increase the rate of heat dissipation appreciablyover that or prior art thermionic tubes.

Other objects, advantages, and inherent functions of the invention willbecome apparent as the invention is more fully understood from thefollowing description, which, taken in connection with the accompanyingdrawings, disclose a pre-' ferred embodiment of the invention.

The accompanying drawings illustrate a preferred embodiment of theinvention in which Figure l is an elevational view of the preferredembodiment of the invention;

Figure 2 is an enlarged elevational view of the plate assemblyillustrated in Figure 1; and

Figure 3 is a top plan view of the plate assembly illustrated in Figure2.

The drawings of the preferred embodiment show a conventional generalpurpose radiation cooled triode or three element thermionic tube. Inaccordance with usual practice, the triode is provided with a base Iwhich is secured to a glass envelope 2. There is mounted within theglass envelope 2 a filament or cathode 3. Filament leads 4 connectopposite ends of the filament to filament terminals 5, the filamentterminals 5 being located at the bottom of the base I. A grid 6surrounds the filament 3 and is connected through a grid lead I to agrid terminal 8 mounted in the side wall of the glass envelope 2. Aplate or anode 9 surrounds the grid 6 and is connected through a plateor anode lead ill to a plate or anode terminal ll located at the top ofthe glass envelope 2.

The structure and operation of triode thermionic tubes of the typegenerally described above are well known to and understood by mechanicsskilled in the art and provide a suitable environment for the inventionhereinafter described. It is also well known to skilled mechanics thatall of the power fed to the plate of a thermionic tube is not convertedinto usable power. Part of it is wasted in heat within the tube. Inthermionic tubes there is a limit to the amount of power that a tube candissipate in the form of heat without danger of damage to the tube. lheamount of this power is known to mechanics skilled in the art as themaximum rated plate dissipation of the tube. In the past,

the prior art has suggested many expedients intended to increase themaximum plate dissipation of thermionic tubes. These expedients includea multitude of endeavors. For example, some prior art tubes have usedfinned plates or anodes, .and other prior art tubes have used plates oranodes coated with various kinds of materials. None has been whollysatisfactory.

This invention relates to a new and improved means of increasing themaximum plate dissipation of thermionic tubes and does it in a moreefficient way than known prior art expedients. More specifically, thepresent invention comprehends a plate or anode assembly which includesan inner cylinder I2, the inner surface of which acts as the anodesurface. An outer cylinder l3 surrounds the inner cylinder l2 and is'arranged in coaxial alignment with the inner cylinder. The lower edgesof the two cylinders are secured by means of a roll weld I4, and theupper ends of the two cylinders are secured by means of an openlattice-like web support 15. The web support It may be secured to theinner cylinder 12 and the outer cylinder I 3, for example, by means ofspot welding. The upper end of the inner cylinder I2 is closed by meansof a dome shaped cover Hi.

The dimensions and materials of the plate assembly are not critical andmay vary widely without affecting the desired results. For example only,it has been found that a very satisfactory plate structure for a tubehaving a height of 12% inches and a normal plate dissipation of 450watts, is obtained by forming the plate assembly with the inner diametera. of the inner cylinder I2 of 1.500 inches, an outer diameter b of theinner cylinder [2 of 1.531 inches, an overall height 0 of the twocylinders of 2.125 inches, a height 11 of the dome l-6 of .500 inch, anouter diameter e of the outer cylinder l3 of 1.875 inches, and a heightf of the lattice-like web support [5 of .187 inch. For example only, ithas also been found that satisfactory metal for the plate assembly istantalum. A number of other metals may be used, such as for example onlymolybdenum, tungsten and other pure metals or alloys.

In conjunction with this plate assembly it has also been found useful toconstruct the glass envelope 2 of glass which will transmit in theneighborhood of of infra-red rays having a wave length shorter than 2.6microns and to operate the plate at such temperatures, say in theneighborhood of 1037 centigrade, that the peak wave length of the wavesproduced by said plate structure is shortened to 2.2 microns. Suitableglass having the foregoing properties is well known to mechanics skilledin the glass art and need not be described herein. Moreover, skilledmechanics in the thermionic tube art are able to select the propervoltage and current requirements to arrive at the suggested platetemperature, hence no details of voltage and current requirements aregiven.

It has been found by actual tests that thermionic tubes using the plateconstruction of this invention have a plate dissipation more than doublethat of otherwise identical tubes using the prior art finned plateconstruction and that such tubes have an increased useful life over suchprior art tubes.

Although the plate assembly'is illustrated in association with a triodetype thermionic tube and although specific dimensions and materials arestated, it will be understood that the invention has like utility inassociation with thermionic tubes having more or less than threeelements and that difierent dimensions and materials may be used. Itwill be understood further that other embodiments of this invention mayexist and that changes within the ambit of the claims may be madeWithout departing from the scope of this invention.

What is claimed is:

1. In a thermionic tube, a plat assembly having a metallic inner tubularanode, a metallic outer tube spaced from and surounding said anode, acontinuous metallic joint connecting one end of said anode to thecoresponding end of said outer tube, and a metallic lattice-like websupport connecting the other end of said anode to the corresponding endof said outer tube, the space between said anode and outer tube beingfilled only with the atmosphere of said thermionic tube.

2. In a thermionic tube, a plate assembly having a metallic innertubular anode, a metallic outer tube spaced from and surrounding saidanode, a metallic lattice-like web support securing one end of the saidanode to the corresponding end of said outer tube, and a dome like coverclosing the end of said anode adjacent the end whereon there is securedsaid lattice-like web support, the space between said anode and outertube being filled only with the atmosphere of said thermionic tube.

3. In a thermionic tube, a glass envelope adapt ed to transmit in theneighborhood of 90% of infra-red rays having a wave length shorter than2.6 microns, and a plate assembly normally operable at a temperaturewhereat the peak length of the waves produced by said plate assembly isin the neighborhood of 2.2 microns, said plate assembly having ametallic inner tubular anode, a metallic outer tube spaced from andsurrounding said anode, and a continuous metallic joint connecting oneend of said anode to the corresponding end of said outer tube, the spacebetween said anod and outer tube being filled only with the atmosphereof the tube.

4. In a thermionic tube, a glass envelope adapted to transmit in theneighborhood of 90% of infra-red rays having a wave length shorter than2.6 microns, and a plate assembly normally operable at a temperaturewhereat the peak length of the waves produced by said plate assembly isin the neighborhood of 2.2 microns, said plate assembly having ametallic inner tubular anode, a metallic outer tube spaced from andsurrounding said anode, a continuous metallic joint connecting one endof said anode to the corresponding end of said outer tube, and ametallic lattice-like web support connecting the other end of said anodeto the corresponding end of said outer tube, the space between saidanode and 4 outer tube being filled only with the atmosphere of saidthermionic tube.

5. In a thermionic tube, a glass envelope adapted to transmit in theneighborhood of of infra-red rays having a wave length shorter than i2.6 microns, and a plate assembly normally operable at a temperaturewhereat. the peak length of the waves produced by said plate assembly isin the neighborhood of 2.2 microns, said plate assembly having ametallic inner tubular anode, a metallic outer tube spaced from andsurrounding said anode, a metallic lattice-like web support securing oneend of the said anode to the corresponding end of said outer tube, and adome like cover closing the end of said anode adjacent the end whereonthere is secured said lattice-like web support, the space between saidanode and outer tube being filled only with the atmosphere of saidthermionic tube.

6. In a thermionic tube, a'plate assembly and a glass envelope adaptedto transmit in the neighborhood of 90% of the infra-red rays produced bysaid plate assembly, said plate assembly normally operable at atemperature whereat the peak length of the waves produced by said plateassembly is in the neighborhood of 2.2 microns, said plate assemblyhaving a metallic inner tubular anode, a metallic outer tube spaced fromand surrounding said anode, and a continuous metallic joint connectingone end of said anode to the corresponding end of said outer tube, thespace between said anode and outer tube being filled only with theatmosphere of the tube.

7. In a thermionic tube, a plate assembly and a glass envelope adaptedto transmit in the neighborhood of 90% of the infra-red rays produced bysaid plate assembly, said plate assembly having a metallic inner tubularanode, a metallic outer tube spaced from and surrounding said anode, acontinuous metallic joint connecting one end of said anode to thecorresponding end of said outer tube, and a metallic lattice-like websupport connecting the other end of said anode to the corresponding endof said outer tube, the space between said anode and outer tube beingfilled only with theatmosphere of said thermionic tube.

8. In a thermionic tube, a plate assembly and a glass envelope adaptedto transmit in the neighborhood of 90% of the infra-red rays produced bysaid plate assembly, said plate assembly having a metallic inner tubularanode, a metallic outer tube spaced from and surrounding said anode, ametallic lattice-like web support securing one end of the said anode tothe corresponding end of said outer tube, and a dome like cover closingthe end of said anode adjacent the end whereon there is secured saidlattice-like web support, the space between said anode and outer tubebeing filled only with the atmosphere of said thermionic tube.

WELTIS WIHTOL.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,962,218 Snow June 12, 1934 1,988,398 Saxl Jan. 15, 19352,407,857 Verhoeff Sept. 17, 1946 2,423,815 Ramsay July 8, 19472,466,430 Hutchison Apr. 5, 1949 2,466,967 Pressel et al. Apr. 12, 1949FOREIGN PATENTS Number Country Date 142,582 Switzerland Dec. 1, 1930

